JPH0677963A - Communication system and terminal equipment - Google Patents

Abstract

PURPOSE:To provide a multiplex access system impartial in plural terminals and high in communication efficiency. CONSTITUTION:A slave equipment transmits the number of fragments and the present address to a request area R2 of a communication frame 30, and a master equipment transmits the address of the slave equipment permitted transmission for each slot 38i in an information transfer area R4 composed of the plural pairs of fragment slots 38 and response slots 39. The slave equipment transmits a destination address 52 and data 54, and a destination equipment transmits the response to the slot 38i. When the master equipment detects the destination equipment fails the reception, the data are transmitted again in the next slot 38i+1. The right of transmission to be reserved and the maximum number of transmitting data in the cycle are controlled by a base station according to the request of the terminal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system and a terminal device, and more particularly to a multiple access system communication system and a terminal device in which transmission rights of a plurality of terminal devices are centrally managed by a main device (control station). .

[0002]

2. Description of the Related Art Conventionally, in a communication system composed of a plurality of terminal devices, a main control station has given a data transmission right to a plurality of terminal devices having a transmission request or an access right to a communication medium (communication channel). The "polling method" and the "time-division multiple access (TDMA) method of fixed allocation" are known as multiple access control methods that are centrally managed.

In the polling method, the main device makes an inquiry to each terminal device (hereinafter referred to as a slave device) about the presence or absence of information to be transmitted. There is an advantage that the slave devices send out the transmission information at the same time, and there is no possibility that they will collide with each other on the communication medium, and that the slave devices can be equally given the access right. However, since a considerable band of the communication medium is consumed by the polling message from the main device to the slave device, there is a problem that the utilization efficiency of the communication medium is reduced.

On the other hand, in the fixed allocation TDMA method, the main device pre-allocates the use time of the communication medium to each slave device, and each slave device is unique to its own device which periodically circulates. Since the data is transmitted in the time zone of, there is no possibility that the transmission information from a plurality of slave devices will collide on the medium, and as in the polling method described above, the master device frequently transmits to the slave device. Since it is not necessary to send a message, there is an advantage that multiple access control is simplified.

However, in the TDMA system, since the time zone peculiar to each slave device is secured even during the period in which data transmission is not performed, data transmission between terminals occurs intermittently, for example, in a LAN. If this is applied to the system, the use efficiency of the communication medium is reduced. In particular, a wireless LA using a wireless terminal as a slave device
In the N system, a slave device frequently joins or leaves the communication area (cell) as the slave device moves, and each time the master device needs to reallocate a band to the slave device. Therefore, the use efficiency of the communication medium is significantly reduced.

[0006] Conventionally, the "divided channel reservation system" is known as one of the techniques for solving these problems. In this method, an access channel (communication frame) is divided into a control information transfer area and a message transfer area, and the control information transfer area is further provided with a transmission request area including a plurality of slots and a response corresponding to each slot. Area, and each slave device uses one of the slots in the transmission request area to request the master device to grant an access right,
In the response area where the main device corresponds to the above slot,
The time zone within the message transfer area in which the slave device can be used is notified. As a specific example of the above-mentioned divided channel reservation system, for example, I, E, E, Network Magazine (IEEE, Network)
k Magazine), Nov. 1991, pp31
-38, "Wireless In-Building Network Architecture and Protocols (Wireless In-Building)
Network Architecutre and
(Protocols) ”(hereinafter, referred to as conventional method 1).

According to the above-mentioned conventional method 1, each slave device, which has obtained the access right by the response operation from the master device, divides the information (message) to be transmitted into a plurality of fixed-length information blocks, and each information block Is set in the fixed length packet area (fragment) called "fragment slot" defined in the message transfer area. The information block set in the fragment is once received by the main device, and the main device sets it in the fragment slot of another communication frame and transfers it to the destination slave device. If the transfer of the information block to the destination device fails, the slave device of the transmission source operates to send the same information block again. A plurality of fragment slots are formed in the message transfer area, and each fragment slot has an information area for setting an information block and information (block number) indicating the position of the information block in one transmission message. And a code area for error correction / detection.

According to the above-mentioned conventional method 1, each slave device which is going to transmit data uses the slotted aloha (Sl) by using an arbitrary request slot defined in the control information area.
The transmission request is made in fragment units by the "OTTO ALOHA" method. If transmission requests from a plurality of slave devices collide with each other in the same request slot, the slave device retransmits one request slot randomly selected in any frame after the frame in which the collision occurs. , Issue a send request.

On the other hand, as a success / failure response method of receiving transmission information from a slave device of a destination to a slave device of a transmission source, conventionally, an acknowledgment (ACK) as an affirmative response when reception is successful.
Pattern, NAK as a negative response in case of failure (NAK)
The method of returning the pattern is common. However,
This response method causes a problem in broadcast communication in which the same information is transmitted to a plurality of slave devices. For example, in a LAN using a ring type transmission line, there is a fear that another LAN node may rewrite the NAK pattern into an ACK pattern on the downstream side of the LAN node that issued the NAC response. Further, in an Ethernet or a wireless LAN in which the same communication medium is shared by a plurality of devices, response signals output from a plurality of receiving side devices collide with each other on the communication medium, and ACK patterns and NAKs set in the response area are set. There is a fear that the pattern will be transformed into another pattern.

As one of the conventional techniques for solving these problems related to reception success / failure, for example, in pp 623-626 of the 13th "Information Theory and Its Application Symposium", "Multicast ARQ suitable for mobile communication environment" On the other hand, a proposal entitled "One-sided Expression" (hereinafter referred to as Conventional Method 2) has been made. In the conventional method 2, each device returns the NAK signal only when the reception of the broadcast information fails. Further, in order to reduce the collision probability of NAK signals output by a plurality of devices, a wide response area is set so as to allow a plurality of responses, and even if a collision occurs, the response signals are retransmitted within the same frame. It can be repeated.

By the way, in a wireless network,
It is generally known that the received power of an antenna attenuates in inverse proportion to the square of the distance ratio between the transmitting and receiving devices. Therefore, when a plurality of slave devices with different distances from the master device send signals to the master device with the same transmission power, the received power observed by the master device is different for each slave device. Becomes For example, when two slave devices A and B located at positions 1 m and 10 m respectively from the master device transmit with the same power, the power of the signal received by the master device is from slave device A to slave device B. It is 100 times larger than the one.

Therefore, when the above-mentioned conventional method 1 is applied to a wireless network, when transmission requests issued by a plurality of slave devices collide on the same request slot, depending on the position (distance) relationship between the master device and the slave device, The following two situations occur in receiving a transmission request. In the first situation, a plurality of transmission requests are mixed with substantially the same reception power, so that all the transmission requests are determined as error signals. In the second situation, the signal having the maximum received power among the plurality of transmission requests is correctly received and processed. As can be seen from the distance characteristics of the received power described above, unless there is a radio wave shield between the slave unit and the master unit, the transmission request from the slave unit closest to the master unit has priority over other slave units. Is more likely to get.

For example, a case where two slave devices A and B having the same transmission power transmit a packet having a length of 100 bits at the same time and arrive at the main device as signals a and b having reception powers Sa and Sb, respectively. Suppose. Here, when the signal b is regarded as noise with respect to a, Sa / (N + Sb) <α, (α is the bit error rate 1E-2
The above second situation occurs because the probability that the signal a is detected as a normal signal by the main device is high when the relationship of the SN ratio) is satisfied.

Reference "Digitalization Technology of Mobile Communication", p.
According to "Error rate-SN ratio characteristic" described in 76 (Trikeps), the value on the right side of the above equation is about 9 dB in QPSK with differential detection, and Sa = r × r × Sb,
Sb / N (Error rate 1E-4 obtained on average in the wireless section
Since))> 1, the distance r ≧ 2.8 m. In the wireless network, the communication coverage area of the main device generally has a radius of about several tens of meters to several hundreds of meters, so that the second situation can easily occur in an actual application.

However, the second situation is unfair access control because the transmission right is preferentially given to a specific slave device when the transmission requests conflict with each other. The document of the conventional method 1 does not mention a solution for realizing fair access control irrespective of the position of the slave device.

The inaccessibility of access control caused by the second situation can be solved by controlling the transmission power of each slave device so that the reception power of the master device becomes constant, for example. In such a case, according to the conventional general control method, each slave device monitors the magnitude of the received power from the main device, estimates the distance from the main device based on the value of the received power, and transmits it. I try to control the power. A specific example of this type of transmission power control system is, for example, IEEE VTS'91 Proceeding.
s), p57-p62, “On the System Design Aspects of CDM Applied to Digital Cellular and Personal Communications Networks (On
The System DesignAspects
of Code Division Multiple
Access (CDMA) Apply to
Digital Cellular and Pers
onal Communications Network
rks) ”(prior art 3).

[0017]

The method of transferring all the transmission information from the slave apparatus to the destination apparatus via the main apparatus as in the above-mentioned conventional method 1 has the advantage that the communication management can be centrally processed by the main apparatus. In particular, when applied to a wireless LAN, there is an advantage that the occurrence of hidden terminals peculiar to the wireless LAN can be reduced. That is, in the method of directly communicating between the terminals, if there is an obstacle between the transmitting side device and the receiving side device, communication will be lost, but if the method of passing through the main device is used, Are arranged at positions that can be seen from the respective slave devices, so that they can be prevented from being affected by obstacles between the transmitter and the receiver.

However, in the above conventional method 1, the "upstream communication channel" from the slave device to the main device and the "downstream communication channel" in the opposite direction are separate channels that are independent in frequency or time. You need to prepare. Therefore, compared to the method of directly transmitting / receiving a communication signal between slave devices, the communication efficiency is reduced to half, and there is a problem in effective use of transmission resources.

In a wireless LAN, the size of each fragment is generally about several hundred bytes, but the maximum length of a message sent from each terminal device (slave device) using the wireless LAN is the above. Since the size of a fragment is about 1.5 kbytes to 10 kbytes, which is much larger than the size of a fragment, if the method of issuing an access right acquisition request in fragment units as in the above-described conventional method 1 is adopted, each terminal device has 1 It is necessary to perform the access request operation several times to several tens of times for transmitting one message. This access right request operation is necessary even when the same information block is retransmitted. Therefore, when the above-mentioned conventional method 1 is applied to a wireless LAN, the collision probability of access right requests in the request area increases, and as a result, However, there is a problem that the communication efficiency is reduced.

Further, in the communication frame structure of the above-mentioned conventional method 1, since the receiving side device does not have a special area for notifying the transmitting side device of the response information indicating the success or failure of the reception of the fragment, the receiving side device , The transmission side device is obliged to acquire the fragment slot by the same method as the access operation performed at the time of transmitting the fragment and transmits the response information, which is also one of the deterioration of the communication efficiency and the increase of the transmission waiting time. It becomes a factor. Further, if the response from the receiving side device is delayed, as a result, the end-to-end throughput is lowered. As an example of a data retransmission method for the purpose of preventing a decrease in communication efficiency due to response delay, for example,
Selective Retransmission (Selective Re) that retransmits only the fragments that could not be received.
The transmission method is known, but this retransmission method has a problem of requiring a complicated buffer management function for each terminal device.

If the fragment area in the communication frame is designed to be short, the fragment header occupies a large proportion, so that the size of each data block becomes relatively small and the transmission efficiency decreases. If it is designed to be long, the probability of data retransmission due to data transmission failure increases, and the amount of retransmitted data also increases, so transmission efficiency decreases. That is, regarding the fragment length, there is an optimum size range determined from the viewpoint of communication efficiency for each system.

On the other hand, in the LAN system, the protocol of the logical link control (LLC) layer and above has a structure that does not depend on the type of transmission medium.
L from the media access control (MAC) layer
The interface to the LC layer usually requires high quality with a bit error rate of 1E-8 or higher. Therefore, for example, a wireless LAN having an average bit error rate of about 1E-4
Then, it is necessary to perform error correction in the layers below the MAC layer to improve the bit error rate of 1E-4 to 1E-8 or more. Therefore, for example, a Hamming code or a BCH code is applied as the correction code. In this case, considering that the coding rate and the raw error rate in the hidden terminal environment are about 1E-2 or less, the correction is performed. Number 10 in blocks
You need to prepare a bite. Therefore, in the frame structure of the conventional method 1 in which the structure of the fragment has only one error correction / detection area, the fragment length is limited by the size of the correction block, and the actual fragment length is the same as the above-mentioned retransmission of the error block. Since it becomes much shorter than the optimum fragment length calculated from the header overhead, it is difficult to obtain the maximum communication efficiency as long as this fragment structure is adopted.

Further, one of the other factors that govern the communication efficiency in the divided channel reservation system is the success rate of access requests in the request area. When the number of request slots provided in the request area in each communication frame is increased, the access request success rate is apparently improved, but in this case, the size of the request area is increased and the message transfer area (or information area) Because the size decreases
It does not necessarily lead to substantial improvement in communication efficiency. Therefore, in an actual system, an access request retransmission procedure when a plurality of access requests collide in the same request slot,
In other words, the quality of the backoff algorithm greatly affects the communication efficiency. However, according to the conventional method 1, while the operation of retransmitting the access request due to the collision is repeated, a new access request is generated from another slave device, which further increases the collision probability, resulting in the system. May fall into congestion.

On the other hand, in the conventional method 2 relating to the reception response of the broadcast communication, it is impossible to set the collision probability of NAK to zero, and the collision problem is not essentially solved. According to the above method, when the size of the communication frame is limited, the message transfer area has to be narrowed by the increase in the response area, which causes a problem that the communication efficiency is rather lowered.

Further, in the indoor wireless communication environment, since the transmitted wave is reflected by the wall or the like, the same signal overlaps the plurality of paths and arrives at the receiving device side. The path of radio waves is affected by, for example, opening and closing of doors, fluctuations of blinds and curtains, movement of people, etc., which changes the phase relationship of radio waves that overlap with each other, and strengthens or cancels each other to cause amplitude fluctuations. It has been known. In this case, the fluctuating frequency (Doppler frequency) is about several tens Hz, but the frequency of the communication frame is also generally about several tens Hz. Therefore, even if each slave device tries to control the transmission power based on the reception power from the master device, it is difficult to accurately estimate the actual transmission power because the estimated time and the transmission time difference are about the fluctuation period. is there.

The above-mentioned problem of unfair access control due to the difference in received power in the wireless network is compared with the access control method based on collision in Aloha, Slotted Aloha, CSMA or CSMA / CD in a wired network environment. Then, it is hard to say that it is unfair. That is, in a wired network environment, each terminal always fails to communicate when an access request collides. Therefore, even in a wireless network environment, even if communication fails when an access request collides with another terminal, the wired network Same as the case. Rather, it is considered that the communication efficiency is improved because the terminal device located near the main device has a chance to win the competition with other terminals. The essence of unfair communication opportunities is not that there is a terminal that survives competition, but that the terminal device that survives is specified by the slave device that is closest to the main device.

Even if the power control shown as the prior art 3 can deal with unfair access, it is practically difficult to apply it to a wireless network to accurately control the transmission power of a slave device. Even if the transmission power can be controlled, as a result, the above-mentioned remaining unsuccessful opportunity is taken and the communication efficiency is reduced, so that it is not necessarily an optimal method.

In a local network in which a plurality of communication devices contend for a transmission right and only the device having the transmission right transfers data, the transmission priority can be given to each communication device. A control method is known. For example, in the IEEE 802 standard token ring, a priority bit is provided in each packet. Also, CSMA /
In the CD as well, for example, a collection of lectures by the Institute of Electronics and Communication Engineers (1981) 1-276 and the Journal of Information Processing Society Vol.
23, No. 12, 1982, p1140, priority CSMA / CD is introduced.

However, each of these priority controls requires complicated control at the MAC layer level, and
It cannot be applied to a network access control method such as MA and slotted aloha, which is premised on the collision of a plurality of access requests and in which each terminal does not have a collision detection capability.

A first object of the present invention is to provide a communication system with improved communication efficiency, in which an access request from a slave device to a data transmission channel can be controlled by the main device.

A second object of the present invention is to provide an improved terminal device capable of efficiently communicating especially in a wireless LAN.

A third object of the present invention is to provide an access control system which enables each slave device to easily acquire an access right to a communication channel in a communication system composed of a master device and a plurality of slave devices. It is in.

A fourth object of the present invention is to provide a communication system which comprises a main device and a plurality of slave devices and which can efficiently perform a transmission information retransmission operation or a broadcast communication information reception response. It is in.

A fifth object of the present invention is to provide an access control system capable of imparting access rights fairly without performing dynamic transmission power control depending on the distance from the main device in each terminal device. To do.

A sixth object of the present invention is to provide a priority control method suitable for a wireless network system which does not require processing at the MAC layer level.

[0036]

In order to achieve the above object, the communication system of the present invention comprises a master device for controlling access right and a plurality of slave devices, and between these slave devices and between the slave devices and the slave device. In a communication system in which communication between devices is performed using a communication frame including at least a synchronization signal area, a request area, and an information transfer area, each slave apparatus that is to transmit a message accesses in the request area of the communication frame. A request is issued, access permission is obtained from the main device in a predetermined area of the same communication frame, and data can be immediately transmitted using the information transfer area of the same communication frame. 1
In one communication frame, the request area is composed of a plurality of request slots, and the information transfer area is composed of a plurality of fragment areas.

According to the present invention, each slave device having a message to be transmitted receives, for example, a predetermined signal pattern sent by the master device in the synchronization signal area of each communication message,
A data transmission request (access request) including the identifier of the own device that is the data transmission source is transmitted in an arbitrary request slot within the request area identified based on this. The access request signal sent by the slave device in each request slot in the request area is received by the master device.

The master device temporarily stores the access request from the slave device, and sends the access permission information to each slave device in the information transfer area defined after the request area in the communication message. . The fragment area included in the request area is composed of a first part for setting access permission information and a second part for setting subsequent transmission information, respectively, and the main device is associated with the first part. The above-mentioned access permission information addressed to the slave device is issued in a format in which the identifier of the slave device permitted to use the fragment area is set.

Each slave device which has transmitted the access request monitors the first part of each fragment area included in the request area, and when its own identifier is detected here, the access permission of the fragment area is obtained. Then, the packet information (fragment) including the header information including the identifier of the destination device of the message and the transmission information (data block) is transmitted to the second portion following the first portion.

Since the message to be transmitted from each slave device is generally longer than the data block size that can be transmitted in one fragment area, it is necessary to acquire a plurality of fragment areas for transmitting one message. Therefore, according to one embodiment of the present invention, each slave device specifies the number of fragments required for message transmission at that time in the access request signal sent to the request area, and the master device performs communication. The access request (fragment number) from a plurality of slave devices requested in the request area of the frame is scheduled and the access permission is given.

As a result, if the situation permits, one slave device is given access permission for a plurality of consecutive fragment areas in the same communication frame, and the slave device permitted to access the transmission message. The plurality of data blocks can be transmitted by using the plurality of fragment areas in the same communication frame.

If the total number of fragment areas requested by the slave device in the access area of one communication frame is larger than the number of fragment areas prepared in each communication frame, the main device makes an access request. Access permission of the fragment area is given to the slave device in a continuous form from one communication frame to the next communication frame. In order to effectively use the fragment area, all access requests issued by the slave device in one communication frame may be accepted, and permission for this request may be given in a communication frame generated thereafter.

One feature of the present invention is that the transmission information sent by each slave device to the fragment area is temporarily stored by the master device for retransmission. When the destination slave device fails to receive the transmission information, these pieces of transmission information are sent to the fragment area by the main device and received by the destination device.

To judge whether or not the destination slave device has correctly received the transmission information, for example, a response area is defined following the transmission information area (second part) for each fragment area of the communication frame. The destination slave device may set information indicating whether or not the transmission information has been successfully received in the response area, and the main device may monitor the information.

According to the above frame structure, the main device issues access permission in the first part of a certain fragment area, the transmission source slave device which detects the access permission sends out the transmission information to the second part, and the subsequent response area. When the destination slave device responds and there is a NAK response indicating poor reception, the master device retransmits the transmission information with the poor reception instead of the source slave device in the next fragment area. Can work. In this manner, when the main device retransmits the transmission information having the reception failure instead of the source slave device, for example, in a wireless LAN, an electric wave from the source slave device causes an electric wave from the source slave device due to an obstacle. Even if it is in a state where it does not reach the destination (the state of the hidden terminal), the radio wave from the main device is normally received normally by the destination slave device, so the destination slave device normally receives and responds to the resend information. It is possible to increase the probability.

Another feature of the present invention is the format of the information transfer area of the communication frame. According to one embodiment, the communication frame identifies, in each fragment area described above, new information or retransmission information in the header portion of the transmission information (hereinafter, simply referred to as fragment indicates this transmission information). It has an information field, an error detection code field at the end of each fragment area, and a response area for setting the response information from the destination device described above immediately after each fragment area. ing.

According to the above communication frame format,
When the destination slave detects that there is an uncorrectable data error in the received fragment, it sends a NAK response in the response area that is paired with the received fragment area.
A request for resending the fragment can be promptly made. Further, when the same transmission information is transmitted to a plurality of slave devices in a broadcast communication format, for example, the response from the reception side device is limited to the NAK response indicating the reception failure.
Even if NAK responses from a plurality of devices collide with each other in one response area, the main device that detects the collision can judge that the broadcast communication has failed and retransmit the broadcast information.

In the preferred embodiment of the present invention, the transmission source device divides the transmission information (fragment) set in each fragment area into a plurality of relatively short correction blocks and generates a correction code in units of each correction block. . In an environment where the transmission quality is extremely inferior, all the correction blocks in one fragment area may not be completely error-corrected, and retransmission requests may frequently occur. As a device for reducing the number of retransmission requests below, for example, a slave device or a master device, which is a transmission side device, transmits the same transmission information to a plurality of correction blocks in one fragment area or to all correction blocks. If a transmission mode (“block repeat transfer mode”) that can be set is prepared and the destination device normally receives data from any one of the above correction blocks, another block that cannot be error-corrected Even if there is, a NAK response should not be issued. In this case, the fragment transfer mode is notified to the receiving side device by, for example, setting identification information in the mode field provided in the header part of each fragment area.

Still another feature of the present invention is that, when a plurality of access requests collide (compete) with each other in one request slot in the request area, the main device which detects this conflicts with, for example,
Control information indicating that access requests from other devices other than the device that failed the access request in the previous communication frame can be temporarily set in the request area of the next generated communication frame. It is in. The access request is temporarily prohibited, preferably when the number of request slots in a race condition exceeds a predetermined threshold value, and when the number becomes less than a predetermined value, the access request is prohibited in the request area. The control information indicating cancellation is set.

In the access control method according to the present invention, when a plurality of access requests compete for the same request slot, the access request (transmission right) by the same slave device is exclusively used on the assumption that there is a device that can survive the competition. It is characterized by controlling so as not to become. The access request restrictions are
For example, the maximum value (window) of the number of access requests that each slave device can exercise within a predetermined period (limit cycle) is determined, and for the slave device whose access request count reaches the window value in the same cycle, Access requests are prohibited until the next cycle. Instead of the access request, the number of fragments that can be acquired or reserved may be limited.

In the embodiment of the present invention, the main unit dynamically changes the access request restriction cycle according to the communication status between the terminals. For example, the main device monitors the request area of each communication frame, the number of access requests from the slave device is zero before the limit cycle expires,
Alternatively, when it is detected that the value is below a predetermined threshold,
By switching to a new cycle, the waiting time is shortened and an opportunity for a new access request is given to the slave device that has already reached the window value and is waiting for the next cycle.

The information indicating that the restriction cycle has been updated is output by the main device to a predetermined area of each communication frame, for example, a part of the synchronization signal area. The slave device waiting for the update of the limited cycle monitors the cycle information, and when the limited cycle is updated, returns the window value to the maximum value and restarts the management of the number of access requests. As the cycle information, for example, a sequence number updated every cycle is applied. Alternatively, the flag may be set in the communication frame immediately after the cycle update.

In the preferred embodiment for dynamically updating the limit cycle, an inquiry area to the slave device is defined for each communication frame separately from the request area, and the slave device is accessed in the area in the next communication frame. Queries the necessity (plan) of the request, and if the number of access requests scheduled for the next communication frame is zero or less than a predetermined threshold, update the limit cycle in the next communication frame. It is characterized by having done. By doing this, it is possible to determine whether or not the limited cycle update is required by one frame earlier than when checking the presence or absence of an actual access request in the request area. It is possible to expedite the restriction release of the access request to the device.

In order to achieve the priority control in the wireless network system, when the access requests contend with each other, the device having the higher priority can be controlled so as to be surpassed by the other slaves having the lower priority. That is, the transmission power of the slave device may be controlled so that the priority order and the reception power intensity of the main device are proportional to each other. Therefore, in the modified example of the present invention, a first communication mode with normal transmission power and a second communication mode with stronger transmission power than the first communication mode used by a slave device with a high priority are prepared, and competition occurs. Sometimes, the access request in the second communication mode is made to survive. Each device may be configured to have one of these two types of communication modes fixedly, or to have two types of communication modes so that either one can be selectively used during transmission. May be.

[0055]

According to the communication system and the access control system of the present invention, the slave device defines a fragment area as an information transfer area behind the request area of each communication frame which issues an access request, and the main device defines each fragment area. First of
Since the access right is given to the slave device in the part and the slave device having the access right transmits the information block in the second part of the fragment area, each slave device can quickly send a message with a short waiting time. Can be output processed.

When the present invention is applied to a wireless LAN, the transmission information output from the slave device on the transmitting side to the fragment area is received by the main device and another slave device within the radio wave propagation range. Is located within a range where the transmitted radio wave can be directly received, high transfer performance can be obtained as compared with the method of communicating the transmission information to another slave device via the main device.

Even if the transmitting slave device and the destination slave device are in the same communication space, the destination slave device may temporarily fall into a hidden terminal state due to an obstacle existing on the way, but according to the present invention. For example, if the master device temporarily stores the transmission information received in each fragment area, and if there is a resend request from the destination slave device in the response area defined in the third part of the fragment area ( Or if there is no normal reception response), the main device retransmits the corresponding transmission information using the next fragment area, without re-assigning the access right to the transmission source slave device or performing the band reallocation operation, The resend operation can be completed. In this case, in the communication between the master device and the destination slave device, since the influence of the obstacle that causes the communication failure between the slave devices is small, the possibility of communication failure recurrence is low.

Further, since the retransmission operation of the already transmitted information is performed in the fragment area next to the fragment area in which the reception is defective, the receiving side apparatus should wait for the fragment immediately after the retransmission request as the reception processing. . This method is called Stop and Wait (Stop and wait).
Similar to the Wait) resending method, the required buffer amount of each slave device is small and the control is simple. In a network with a transmission rate of, for example, several tens of Mbps and a communication radius of an area under the control of each main device of several tens of meters, the next information block is transferred after waiting for a response from the receiving device, as described above. There is almost no decrease in throughput due to the execution.

When the communication system of the present invention is applied to broadcast communication, when retransmission requests from a plurality of devices collide in one response area, it is determined that the broadcast communication of the fragment has failed, and the main device determines It suffices to retransmit the corresponding transmission information, and it is not necessary to prepare a wide response area for a plurality of devices for the response of the broadcast information.

Further, according to the communication system and the access control system of the present invention, by allowing the occurrence of a device that can survive when the access requests compete with each other, the throughput is improved as a result and the main device is used in the conventional system. It is possible to eliminate the transmission power control of each slave device, which has been performed according to the positional relationship of. In this case, by adopting a method in which the number of access requests for each slave device is restricted in units of a predetermined limit cycle period, an unfairness that temporarily depends on the positional relationship with the main device occurs within each cycle. However, it is possible to provide a communication environment with good throughput without unfairness in the long run.
In addition, in each communication frame proposed by the present invention, when an area for inquiring about the presence or absence of an access request (transmission right reservation) in the next frame is provided separately from the request area, the main device transmits the transmission right reservation status in the inquiry area. By monitoring the above, the waiting time of the slave device due to the above-described restriction on the number of access requests can be shortened, and the control for dynamically changing the limit cycle becomes possible.

As a modification of the present invention, the slave device has the first and second transmission modes having different power values in order to intentionally utilize the generation of the unsuccessful remaining device at the time of the contention of access requests as described above. The device communicates in a first transmission mode, a device with a higher priority, in a second transmission mode,
It is possible to allow an access request from a device having a high priority to be accepted even when the access requests conflict with each other.
Even in this case, by setting a restriction on the number of access requests within the restriction cycle described above, it is possible to eliminate unfairness among devices, and to improve the throughput by eliminating the failure of access requests due to contention. .

[0062]

1 shows an example of the overall configuration of a communication system according to the present invention. Although the present embodiment shows an example of application to a wireless LAN, the communication method according to the present invention does not depend on whether a part of the transmission path is wired or wireless. For example, the wireless terminal 2 (which is a slave device) Instead of 2a to 2d), the present invention can be applied to a bus type network system having a configuration in which a plurality of terminals are connected to the backbone transmission line 1 via a wired communication line.

In the network of FIG. 1, the base stations 3a and 3b, which are main devices, are connected to the backbone transmission line 1 by coaxial lines 1a and 1b. Reference numerals 4a and 4b denote jurisdiction areas (cells) of the base stations 3a and 3b, respectively. The base station 3a in the cell 4a and the wireless terminals 2a and 2b that are slave devices, and the base station 3b and the wireless terminal 2c in the cell 4b, 2d performs intra-cell communication using a frequency unique to each cell. Between slave devices located in the same cell, for example, the wireless terminal 2
The communication between a and 2b is basically performed by the direct information transfer path indicated by the broken line 5. In addition, communication between slave devices that belong to different cells, for example, between the wireless terminals 2a and 2c (inter-cell communication) is performed via the base station 3a and 3b in each cell and the route 6 that passes through the backbone transmission line 1. Is done.

FIG. 2 shows an example of the configuration of a communication frame 30 used for communication in a wireless section in the above communication system. This communication frame 30 includes a synchronization signal area R1 and a request response information area R for transmitting information from the base station.
2, a request area R3 in which each terminal sends an access request, and an information transfer area R4 in which access permission information from a base station, transmission information from a transmission source terminal, and reception response information from a destination terminal, which will be described later, are transmitted. The base station determines the transmission timing of each communication frame.

The synchronization signal region R1 has a protection period (GT) 32 for absorbing a timing shift between terminals due to a difference in propagation distance from a base station, and "1, 0, 1" having maximum clock timing information. , 0, 1 ... ”A fixed pattern of a preamble (P) 33 and a unique word (UW) 34 of which a fixed pattern for identifying the head position of the subsequent request response information area R2 is set. .

The request area R3 includes a request mode (RM) field 36 and a plurality of request slots (RS) 37. The RM field 36 is the RS
The conditions of the terminal which can make an access request are shown by 37, and the details will be described with reference to FIG.

Each request slot (RS) 37i is
As shown in the figure, the protection area (GT) for absorbing the timing shift due to the terminal position, similar to the GT 32 described above.
40, a preamble part 41 for synchronizing the transmission source terminal and the base station, a request information (RI) setting field 43 for setting an access request for a fragment area, which will be described later, and the beginning of the RI field. And a unique word (UW) 42 for executing.

In each RI field 43, a request number (SN) field 43a in which a request number of modulo 8 is set, and a request source address field (AD) 43b in which an address of an apparatus that has issued an access request is set.
And a field (NF) 43c for setting the number of fragments required to send one message (upper frame) in the request source device, and a request set in the SN field 46a to NF field 46c. A field (CC) 43d for setting an error detection code for information.

In the request response information area R2, the base station responds to the access right grant request requested by the terminal in the communication frame before this communication frame by the base station with an ACK pattern, a NAK pattern, or a rejection (RJ) described later depending on the method.
T) is for setting response information such as a pattern, and is composed of a plurality of response slots (AI) 35a to 35m so as to respond in response to each request slot (RS) 37 in the previous communication frame. ing. Each RS in the request area R3 and each AI in the response area R2
Have a one-to-one correspondence with the positions occupied by them.

The information transfer area R4 has a plurality of fragment slots (FS) 38a to 38n and a plurality of response slots 39a to 3 paired with these fragment slots.
It consists of 9n.

Of these frame components, the base station sets the contents from the protection time (GT) 32 located at the beginning of the frame to the request mode (RM) 44.
In addition, from the protection time (GT) 44 to the destination address (SA) 4 in each fragment slot (FS) 38 described later.
The contents up to 9 are also set by the base station.

Each wireless terminal 2 in the cell uses the phase locked loop (PLL) as a reference for the base station from the pattern of the preamble (P) 33 located at the beginning of each communication frame transmitted by the base station. The clock is extracted and the own terminal clock and the base station clock are synchronized. Also,
Each terminal counts clocks starting from the detected UW 34 and identifies each area in the following frame as well as the boundary of the slot. Fragment slot (F
The details of S) 38 and the response slot 39 will be described later.

FIG. 3 shows the communication system of the present invention.
The communication procedure when two slave devices located in the same cell communicate (intra-cell communication) is shown. Here, the wireless terminal 2a (source terminal) that issued the access request is the wireless terminal 2a.
The case where data is transmitted is shown with b as the destination terminal (destination terminal).

The source terminal 2a requests the fragment slot access right for transmitting the message within the request area R3 of the communication frame, and sets the access request information in any request slot 37i. (Request transmission step 10). The request information includes the address (AD) 43 of the request source device.
b and the number of fragments (NF) 43c required to transmit a message (upper frame) are included.

The base station 3a uses the S of each request slot.
By managing N43a for each terminal, while eliminating double registration of the access request that occurs when the requesting terminal fails to receive the request response information AI described later,
The reception information of each request slot in the request area R3 is temporarily stored (registered), and in the information transfer area R4 that appears thereafter, the source terminal address field 48 defined in the header portion of each fragment slot 38 is written. , The address of the terminal device that can use the fragment as the access permission information is output (allocation slot notification step 10).

The source terminal 2a checks the received address in the source address field of each fragment slot. If the address of its own terminal is detected there, it is determined that access to the fragment slot is permitted except in the case of base station retransmission processing described later, and it is defined in the header part of the fragment slot. The address of the destination terminal 2b is output to the destination address (DA) field 52, and the transmission data is output to the subsequent fixed length transfer information (I) field 54 (data transfer step 12). The transfer data is received by the destination terminal 2b indicated by the destination address 52 and the base station 3a.

The destination terminal device 2b outputs response information indicating success or failure of data reception in a response slot (AS) 39i that follows the fragment slot (FS) 38i in which the data addressed to itself is set (response step 13). ).
If this response indicates successful reception (ACK), the transfer procedure for the fragment ends normally, and the base station allocates the fragment slot to the terminal in the same procedure as described above for the next fragment slot 38i + 1. Notification step 11 is repeated. On the other hand, the response 13
Indicates that data reception has failed (NAK) at the destination terminal 2b, data is retransmitted as follows.

If the base station is able to normally receive the data that the destination terminal 2b failed to receive, the base station performs the data retransmission operation on behalf of the source terminal (base station retransmission step). 14). This data resend operation is
This is realized by outputting the header information and the transmission data already received in the previous fragment slot 38i from the base station to the next fragment slot 38i + 1.

If the base station also fails to receive the data of the fragment slot 38i that the destination terminal 2b failed to receive, the base station allocates the next fragment slot 38i + 1 to the source terminal.
In this case, control information instructing that data should be retransmitted from the transmission source is set in a part (ND field: 46) of the header of the fragment slot 38i + 1 (retransmission slot step 15). When the source terminal 2b receives the fragment slot 38i + 1 including its own address in the source field (SA) 48, if the ND field 46 in the header portion indicates retransmission from the source, the previous transmission is performed. The data block is retransmitted (source retransmission step 16), and if the ND field contains control information for retransmitting at the base station,
Wait for the next fragment slot to come without doing anything.

The above-mentioned base station retransmission step 14 or transmission source retransmission step 16 is repeated until the reception at the transmission destination terminal succeeds or the prescribed number of retransmissions set in advance in the communication system is reached.

FIG. 4 shows a list of reception response operations between the destination terminal and the base station. When the destination terminal succeeds in receiving, regardless of whether the reception at the base station is successful or not 14 ', 16',
The transfer of the fragment is completed. Here, the reception success of the destination terminal refers to the case where the response slot 39i is an ACK response during the individual communication between the terminals and there is no response during the broadcast communication. On the other hand, if the destination terminal fails to receive the data, the “retransmission of base station” 14 is given if the base station succeeds in receiving the data, and the “retransmission of the source” 16 if the base station also fails to receive the data. . Here, "reception failure of the destination terminal"
Indicates that the response slot 39i is "NAK response", "response error", or "no response" in individual communication. However, in order to unify the response procedure of individual communication and broadcast communication, no response may be defined as successful reception.

FIG. 5 shows a transmission message (upper frame) 20 to be transmitted by the terminal which is the transmission source, and transmission information (hereinafter referred to as "fragment") output in one fragment slot 38i. Shows the relationship. The upper frame 20 is divided into a plurality of fixed-length data blocks 20 (20a, 20b, ...), and each divided data block 20 and a header 2 added in front of it.
1 (21a, 21b, ...) and one fragment 23
Is configured. In a wirelessly connected LAN terminal, generally, the upper frame 20 has an LLC layer and a MAC.
It is an LLC frame defined by an interface between layers, and in the wireless connection of the synchronization terminal, each of the above fragments becomes a synchronization frame having a cycle of 125 μsec, for example.

As a fragment slot request method that can be adopted in the communication system of the present invention, for example, there are the following methods. In the first method, each terminal uses a plurality of slots (RS) 37a to in the request area R3.
From 37 m, one slot 37 j is randomly selected for each frame, request information is output to this slot 37 j, and if a request from another device collides, it is re-selected in the request area of the next communication frame. It is a method to issue a request.

The second method is that each terminal outputs request information to a specific slot determined by the address of its own terminal each time a new transmission request is generated, and if it collides with a request from another device. The second and subsequent request requests made in the request area of the subsequent communication frame are performed by randomly selecting slots, as in the first method. This method has an advantage that priority control can be performed based on the terminal address, but the control is slightly complicated as compared with the first method.

In the third method, when a request request of another device collides with the slot in which the request request is output, when a randomly determined waiting time elapses,
It is a method that issues a request. This method has an advantage over the first and second methods in that throughput is less likely to drop in a high load state. On the other hand, there is a drawback that unnecessary access waiting time occurs in the low load state.

When a plurality of terminals simultaneously issue request requests to the same request slot RS37, a collision of request signals causes a code error in the data in the RS, resulting in a terminal that fails the request request. However, in an actual application, when the transmission power of each terminal is constant, the request signal from the terminal near the base station has high reception power, and conversely, the request signal from the terminal located far away has weak reception power. Is received by the base station. Therefore, when the request signals compete on the request slot, the request from the terminal close to the base station may be correctly received without causing a code error. In this case, the base station returns an ACK response to the response slot corresponding to the request slot in which the contention occurred in the request response area R2 of the next frame.

Each terminal that has issued a request request has SA field and D of the fragment slot of each communication frame.
In addition to the A field, I am paying attention to the above-mentioned response slot, and if ACK is set in the response slot corresponding to the request slot that I previously requested in the next communication frame, the access I made last time It judges that the request has been accepted, and waits for its own address to appear in the SA field of the fragment slot without issuing a new access request. Therefore, as described above, when the access requests of the terminals contend with each other when the access requests contend with each other, there is a possibility that the terminal that has lost the competition may perform an erroneous operation with respect to the ACK response.

In order to avoid such an inconvenience, for example, as a first method, as the ACK information set in the request response area R2, the terminal address indicating the issuer of the accepted access request is set to the request response area. As a second method of transmitting data to each terminal, there is a method of controlling the transmission power of each terminal so that the reception power at the base station becomes constant. The control of the transmission power can be realized by, for example, each terminal changing the transmission power according to the reception power from the base station. Comparing the above two methods, the first method has the advantage that it does not require power control, but since the access request acceptance rate differs depending on the positional relationship with the base station, it is unfair to grant the transmission right. Occurs, and some measures are needed to eliminate it.

Returning to FIG. 2, fragment slot 38.
The configuration will be added. Protection time (GT) 44 located at the beginning of the fragment slot (FS) 38
Are provided for switching transmission / reception in each terminal device and for pulling in a synchronization signal. Each terminal device identifies the position of the subsequent new information display (ND) field 46 with reference to the reception time point of the unique word (UW) 45. The ND 46 determines whether the fragment slot is used for the transfer of new data from the terminal (step 12 in FIG. 3) (“new fragment”), the base station retransmission 14, or the source retransmission. It is intended to indicate the division of 16 used.

47 is a fragment number (F) indicating which fragment fragment is for the fragment slot of the number of fragments requested by the terminal device.
N) field. 48 is the source address (SA)
This field is a field that specifies the terminal that has the access right to the fragment slot, and at the same time, indicates the terminal address that is the source of the packet when the fragment slot is regarded as a fixed-length packet. Therefore, the above S
When the ND 46 is for a new fragment, the terminal device which has detected that the A field 48 has its own address, the header information and the data for the area after the SA field 48 and the field 49 and thereafter. Start the sending procedure.

Like the above-mentioned GT 43, the GT 49 secures the time required for switching the operation from the transmission state to the reception state on the base station side and from the reception state to the transmission state on the transmission source terminal having the address SA. It is a protected area. The terminal which is the transmission source transmits the preamble part (P) 50 and the unique word (UW) 51 after the GT 49, then the address (DA) 52 of the destination terminal of the transmission information, and then the data length. (DL) 53 and fragmented fixed-length data (I) 54 are transmitted. (D
L) 53 indicates the length of valid information in the information area 54.
The data section 20 shown in FIG. 5 corresponds to the information area 54, and the header section 21 corresponds to the areas 44 to 53.

Although omitted in FIG. 2, the area from the DA field 52 to the information field (I) 54 is shown in FIG.
As shown in FIG.
It is divided into a to 25e and is provided with error correction codes 26a to 26e using a 9-bit Hamming code for each sub-region, and is composed of five correction blocks with a total length of 511 bytes. The error detection in the area from DA52 to I54 including the correction code is the error detection (CC) using the BCH code.
Detect at 55. Note that in FIG. 2, the numbers attached to the upper part of each field indicate an example of the specific number of bytes in the field.

A terminal device having the address that matches the address in the destination address field (DA) 52 (DA5 above)
When 2 is the code indicating the broadcast communication, the plurality of terminal devices to be received) use the code indicating the success or failure of the reception of the fragment (only when the reception fails depending on the method) as the response slot (the reception slot). AS) 39. The response slot (AS) 39 includes a protected area (GT) 56, a preamble (P) 57, and a unique word (UW) 58.
And response information (AI) 59, and a response code is output to 59. The response method will be described in detail with reference to FIG.

FIG. 7 shows a state transition diagram for frame timing control performed in the base station. The operation state of the base station includes a “frame synchronization state” 61 for outputting the UW 34 from the GT 32 of FIG. 2 and a “request response state” 62 for processing a plurality of (for example, four) request response information (AI) 35. , A request mode (RM) 36 and a “request collection state” 63 that processes a plurality (4) of request slots (RS) 37, and a plurality of pairs (for example, 4 pairs)
Fragment slot (FS) 38 and its response information (AS) 39, and a "transmission / retransmission control state" 64.

The transition between these states is triggered by the timeout of a timer provided for each area (R1 to R4) of the communication frame. For example, if the frame length is about 12000 bits and the transmission rate is 2 Mbps,
The maximum value of the frame timer is about 6 msec.

In FIG. 8, the base station displays the request response status 62.
Alternatively, a request state transition diagram in the terminal when in the request collection state 63 is shown. Each terminal is normally in the “idle (R) state” 65, and when a message transmission request occurs, it transits to the “slot request state” 67 (66) and requests the base station to grant the access right using the request slot. To do. When the transmission of the access request is completed, the base station transits to the "determination waiting state" 70 (68). If any fragment slot in the same frame as the access requested frame is assigned, or if there is an ACK response in the request response information slot (AI) corresponding to the above request slot in the next frame, the request is Judging success, "Idle (R) state" 6
The state transitions to 5 (71). In the case of a NAK response, the state transits to the "slot request state" 67 (69) and the access request is made again.

FIG. 9 shows that the base station is in the transmission / retransmission control state 64.
7 shows a state transition diagram in the terminal in the case of FIG. Normally, it is in the “idle (I) state” 72, but in the request state transition of FIG. 8, if it is in the judgment waiting state 70 or if the request is successful 73, it transits to the “transmission waiting state” 74. In the "idle (I) state" 72 or the "transmission waiting state" 74, there is a possibility of receiving information (75) from another terminal. In this case, the corresponding response processing is performed and the original state is restored. When the fragment slot allocated from the base station is received (77) in the "transmission waiting state" 74, the state transits to the "transmission state" 76. When the fragment transmission using the slot fails, the retransmission 78 is repeated, and when the successful fragment transmission is completed (80),
Return to Idle (I) 72. If the determination is awaited or the successful fragment transmission is incomplete (79), the "transmission state" 76 is transited to the "transmission waiting state" 74, and the allocation of a new fragment slot is awaited.

FIG. 10 shows the request collection performed by the base station.
Also, the procedure for determining the acceptance of the access right granting request in the request response state is shown.

The base station determines whether or not the reception period of the request area R3 of the communication frame 30 has come (step 100). When entering the request area, it is determined whether or not there is an access request (request information) from the terminal. (10
2). If there is request information, the error detection code (CC) 43d is used to make a request slot (RS)
A data error check is performed (104). If the request information is correctly received, the total number of fragments that have already received the request and are currently in the transmission waiting state is referred to, and if the above new access request is permitted, the new fragment number (transmission bandwidth) required. () Is determined (106). If the bandwidth can be secured, an ACK response is returned (110).

If there is an uncorrectable bit error in the request information, if an abnormality is detected in the request number (SN) 43a, or if the bandwidth cannot be secured when the request is received, the request response information area of the next communication frame (R2) At 35, a preparation process for NAK response is performed (108). If there is an abnormality in the request number (SN) 43a, such as a number jump or a duplicate request for a received number, it is considered as a system abnormality. If a system error occurs, A
Instead of the CK / NAK pattern, a reject (RJT) pattern may be returned (120). When the RJT response is issued, the base station initializes the control regarding the abnormal terminal in its own station (122). Also, the above R
The terminal that has received the JT response initializes the control within itself.

FIG. 11 shows an access control procedure in the request area R3 performed by the base station. In this control,
Request mode (RM) field 36 shown in FIG.
Is used to notify each terminal device of prohibition of new access (step 134) or cancellation thereof (step 136). The “prohibit new access” here means that when a request collision is detected in any slot in the request area (130), a terminal other than the terminal involved in this collision is notified of the next communication frame. It means to instruct to prohibit access request in the request area. However, if the communication frames in the request prohibit mode continue for more than a predetermined number of times (132),
In the subsequent communication frame, the request prohibit mode is released (136).

In the above embodiment, new access requests from other terminals are prohibited until the number of consecutive request prohibit modes reaches a predetermined number until collision (competition) of access requests is eliminated. Become. Therefore, in a system in which the number of slots RS36 provided in the request area R3 is smaller than the average number of requests generated, a threshold is set for the number of slots RS in which a collision has occurred, and the slots in which a collision actually occurs. When the number of RSs exceeds the threshold value, new access may be prohibited, and when the number of RSs is less than the threshold value, the prohibition may be released.

When the prohibition (134) of the new access or the cancellation (136) is decided, when the request mode area R3 of the next communication frame is visited (14
0), the notification information is output to the RM field 36 (1
42).

FIG. 12 shows a processing procedure when the terminal device receives a fragment. Destination address field (D
A) When the own device address or the special address indicating the broadcast communication is received in 52 (step 150), the fragment transmits the retransmitted data depending on the contents of the new information display (ND) field 46 already received before that. It is determined whether or not it includes (152). If the fragment has been used for retransmission, it is determined whether the immediately preceding fragment was successfully received (15).
4). If the reception was successful, the ACK response issued in the response area (AS) of the previous fragment did not reach the base station correctly, and the already received fragment was mistakenly retransmitted by the device itself. Then, the received fragment of this time is discarded (156).

When the received fragment this time is found to be new by the judgment of the ND field (15
2; N), or if it is determined that the fragment is a retransmission fragment to the NAK response of the previous fragment (154; N), error detection is performed on the content of the fragment (15).
8). If it contains an uncorrectable error, a NAK response is returned to the response slot (AS) 39i following the fragment 38i to request retransmission of the same fragment (162).

If the received fragment is normal,
This is processed for reception and transferred to the upper layer. In this embodiment, the response operation when a normal fragment is received differs depending on whether the fragment is for broadcast communication or individual communication. In the case of individual communication, an ACK response is output to the response slot 39i (164). In the case of broadcast communication (160; Y), the response slot (AS) 3
In order to avoid ACK responses from a plurality of terminals colliding with each other and causing a response failure in 9i, the transmission of the response pattern to the response slot 39i is omitted. That is, in this embodiment,
In the case of individual communication, the success or failure of reception is positively notified, and in the case of broadcast communication, response information is returned only when reception fails. In the individual communication, if the response is returned only when the reception fails, for example, when the destination terminal is in the hidden terminal state and cannot respond, the transmission source may erroneously determine that the reception is successful. is there.

FIG. 13 is a block diagram showing the basic structure of a base station that executes the above-mentioned access control. The base station is connected to the wired LAN 1 via the backbone interface 211 in order to connect to other base stations, and is connected to each wireless terminal via a wireless channel via the wireless unit reception control circuit 212 and the wireless unit transmission control circuit 213. It is connected.

The frame processing section 214 generates each reference frame of each communication frame based on the operation of generating the reference timing of each communication frame and the signals of the preamble section and the unique word section output from the terminal and received by the reception control circuit 212. Performs field recognition and field information extraction.
The information of the request area R3 extracted from the communication frame is transferred to the request control unit 215, and the information of each fragment slot 38 and the response slot 39 in the information transfer area R4 is transferred to the relay determination unit 216.

The request control section 215 executes the acceptance judgment processing shown in FIG. 10 and transmits ACK or NAK. Depending on the method, the wireless unit transmission control circuit 213 is instructed to transmit the RJT pattern. When an access request from the terminal is accepted, the request is queued.

The relay determination unit 216 refers to the management table based on the destination address of the fragment input from the backbone interface 211 side, and determines whether or not to relay this fragment to the cell (radio area) under its control. judge. The fragment determined to be relayed is stored in the fragment buffer / control unit 217. The relay determination unit 216 includes a frame processing unit 214.
The fragment output from the wireless terminal is also input, and the fragment determined to be relayed is stored in the fragment buffer / control unit 217 as described above. When the abnormal fragment is received and the NAK response is received from the terminal, the relay determination unit 216 sends the NAK response to the state control unit 21.
Notify 9.

The state control unit 219 includes a frame processing unit 21.
In response to the timing of the fragment slot given from No. 4, the wireless transmission control circuit 213 is requested to output the source retransmission request signal.

The fragment buffer / control unit 217
In response to a control signal from the state control unit 219, the radio unit transmission control circuit 213 is instructed to perform relaying from another cell and transmission (including retransmission) of an in-buffer fragment for base station retransmission.

FIG. 14 is a block diagram showing the basic structure of a communication unit included in each wireless terminal. Reference numeral 311 is an interface for connecting a terminal device to a circuit unit that constitutes an upper layer, and control commands and upper frames (transmission messages) received from the upper layer are temporarily stored in the frame buffer / control unit 316. It

The message stored in the frame buffer / control unit 316 is segmented into a plurality of fixed-length data blocks, and the data block to be transmitted is given to the fragment processing unit 317 according to the transmission instruction from the state control unit 319. , Assembled into a fragment with a header as described in FIG. 5, and transmitted from the wireless transmission control circuit 313.

In a situation where the communication environment is bad, it is difficult to recover the code by error correction for all the correction blocks in one fragment, and in the situation where retransmissions occur frequently, an instruction from the state control unit 319 causes the fragmentation. Multiple correction blocks in the same data block,
Data is transmitted in "block repeat transfer mode". The fact that the contents of the fragment are in the block repeat transfer mode means that new information is displayed in the fragment (ND).
By setting the mode identification information in the field 46, the reception partner device is notified.

In this case, in the partner apparatus, the fragment received by the radio section reception control circuit 312 is received by the reception determination / reassembly processing section 315 via the frame processing section 314.
If any of the correction blocks is successfully received, the fragment is received as successful even if there is another uncorrectable block. Although the success or failure of the correction block is performed here by using the error correction / detection code in the block, this may be determined by the majority vote of each block. Also, in each fragment,
The correction block may be divided into a plurality of groups and the block repeat transfer mode may be executed in group units.

The frame received by the radio section reception control circuit 312 from the base station or another terminal is frame-synchronized by the frame processing section 314 and the contents of each field are extracted. The extracted fragment slot is supplied to the reception determination / reassembly processing unit 315, and other information is supplied to the state control unit 319. In the reception determination / reassembly processing unit 315, FIG.
After performing the reception process shown in (1) and reassembling a successfully received fragment into an upper frame (message), the fragment is stored in the frame buffer / control unit 316. The stored upper frame is sent to the upper layer of the terminal via the terminal interface 311. The state control unit 319 controls issuance of a transmission access right grant request and the like according to the state of the control command of the frame buffer / control unit 316.

In the above-described embodiment, each slave device having a transmission request notifies the main device of the required number of fragments and its own address by using the request slot of the frame being received, and the main device schedules the received request. Then, at the output timing of the beginning of each fragment slot in the same frame, the slave device address indicating access permission is transmitted,
The slave device corresponding to this address transmits the destination address and information to the subsequent fields of the fragment slot. According to this method, the base station
Fragment slots can be dynamically allocated according to an access request from a terminal, and information can be directly transmitted / received between terminals. Therefore, M is an ideal characteristic as an access delay time vs. load characteristic. A characteristic close to / D / 1 can be achieved.

When the transmission information is received by both the destination slave device and the main device, and the destination slave device responds that the reception of the fragment has failed, the main device detects this and selects the fragment to be retransmitted. It can be automatically retransmitted in the next fragment slot. The above-mentioned resending operation can be performed by the slave device of the transmission source, but in the case of a wireless LAN in particular, the master device generally has a higher transmission function than the slave device, and there is a communication failure for each terminal device. With the small number of installation position conditions, if the configuration of the above-described embodiment in which the main device performs the retransmission operation, the destination terminal that fails to receive the data from the transmission source slave device is retransmitted from the main device after that. The probability that data can be received normally will be significantly increased. Further, by making it possible to continuously transmit new transmission information, its response, and retransmission information, there is an advantage that retransmission control can be easily realized with a small capacity buffer and simple buffer management.

Next, in the wireless LAN shown in FIG. 1, the second embodiment of the access control of the present invention intended to eliminate the unfairness caused by the position of the terminal and to improve the throughput on the premise of the competition of access requests. Indicates.

In the following description, a communication system using narrow band modulation in which the occupied bandwidth is a bandwidth about the same as the information transmission rate will be described as an example, but the transmission information signal is multiplied by a spreading code and transmitted. A spread spectrum method of direct spread modulation or frequency hopping modulation in which a carrier of a narrow band modulated wave is changed with time according to a spread code may be used. In the case of narrow band modulation, a frequency division method in which the carrier frequency is changed between cells is used. In direct sequence modulation, the frequency is divided or the spread code sequence is changed for each cell, and in frequency hopping modulation, the spread code sequence is changed. The access control method of the present invention described below can be applied to any of these modulation methods. It should be noted that the above-mentioned modulation methods are described in detail in many documents such as "Digital Modulation and Demodulation Technology for Mobile Communication" (Trikeps), and therefore detailed description thereof is omitted here.

FIG. 15 shows a second embodiment of the communication frame 30 used in the wireless communication section.

The communication frame 30 has a frame control area F.
C and a plurality of request slot areas RSi (i = 1 to 1
n), a request area R3, a plurality of response slot areas AIi (i = 1 to n), a request response area R2, an information transfer area R4, and a request display area RI. , And a plurality of fragment response areas ASj (j = 1 to m) paired with the fragment slot areas FSj (j = 1 to m). The base station determines the timing of this communication frame.

The frame control area FC is transmitted from the base station and comprises a preamble (PR) 33, a frame flag (FF) 34 as a unique word, and other frame control information. The preamble 33 is for establishing bit synchronization in each wireless terminal, and has a length of, for example, 40 octets, and the preamble pattern has a unique bit pattern “10101010 10101010 ... 10101010”.
Is used. The frame flag 34 is used by each wireless terminal to establish frame synchronization and octet synchronization, and has a length of, for example, 4 octets, and the frame flag pattern has “10101011 10101011 ... 101”.
01011 ”is used. The frame control information has a length of 5 octets, in this example a base station identifier (BSI) field 331 each having a length of 1 octet,
Request cycle identifier (RCI) field 332
And a request slot number (RSN) field 333 in the request slot area and a fragment slot number (FSN) field 334 in the frame.

Request cycle identifier (RCI)
Is for identifying the update of the limited period (cycle) provided to prevent the exclusive acquisition of the transmission right by the same terminal. In the present embodiment, the request cycle identifier 332 is incremented for each communication frame. When the RCI has an initial value = “00000000” or the CRC 43d is abnormal, each terminal receives the RC already received.
When an RCI different from the value expected from I is received, it is determined that the request cycle has been updated, and the value of the counter (reservation counter) prepared to limit the number of access requests in each request cycle is set. Reset. When the RSN or FSN in which the CRC abnormality has occurred is received, it is processed with the latest value that has not received the CRC abnormality.

The request area R3 is composed of n request slots RS1 to RSn. Each wireless terminal having a transmission message has the above request slots RS1 to RS.
Select any one from n, and 1 for each message
Issue an access request (request). In this embodiment, each of the wireless terminals reserves an access request right (transmission right) in the next communication frame with respect to the base station if the request conflicts with another device and ends in failure. To display the request display area (R
The transmission right reservation is displayed in I). The terminal newly joining the cell also performs its request operation to access its own M database to the accommodating terminal database (location registration DB) of the base station.
Request addition of AC address.

The request slots RS1 to RSn are
A 40-octet-long preamble (PR) 41, a 4-octet-long field flag (FIF) 42, and a total of 8 octet-long other slot information areas 43a-4.
It consists of 3c. The field flag 42 indicates “10101100
10101100 ... 10101100 "is used.

The wireless terminal issuing a request has a 6-octet request address area (RAD) 43b.
The MAC address assigned to the terminal itself is transmitted to the base station. The request attribute area (RAT) 43e has a 2-bit attribute pattern for identifying whether this request is for a fragment request (transmission right reservation request) or an address addition request to the location registration DB, It consists of 6-bit request information that follows this. When the attribute pattern indicates a transmission right reservation request, the number of fragment slots reserved by the request is set as the request information. In addition, the above attribute pattern is the location registration D
When indicating a B addition request, the identifier (BSI) of the base station that is the registration destination is set. A transmission error of information in the request slot is detected by the 1-octet CRC 43d. Note that the MAC address is IEEE
A 6-octet address conforming to the 802 address system can be applied.

The request response area R2 includes a preamble (PR) 41 having a length of 40 octets, a field flag (FIF) 42 having a length of 4 octets, and n request slot response information areas (AI1 to AI1) each having a length of 8 octets.
AIn) 35n.

The base station sets the response result to the access request from the terminal by associating the request slot response information areas AI1 to AIn with the request slots RS1 to RSn in the request area R3, respectively.

Request slot response information area AIi
Is the RAD of the request slot for which an access request was made
6-octet acceptance request address (AAD) field 451 for setting the contents of 43b, 1-octet acceptance status (AST) field 452 for setting acceptance status information indicating the success or failure of the request, and request slot response information It consists of a 1-octet CRC 43d for checking the transmission error inside. In the reception status field, the request success (RA
CK) 521, request failure (RNAK) 522, request rejection (RRJC) 523, no request (NO)
NR) 524 is set to any one of the four states.

The wireless terminal has a response information area AI corresponding to the request slot RSi that issued the access request.
If a CRC error is detected in i, the request is regarded as successful, and if the location registration is requested, it is regarded as failed. When it is determined that the request is successful, timer monitoring is started, and it is monitored that the requested number of fragment slots are allocated in the information transfer area R4 after the communication frame, and when the timer timeout occurs, the access request is made again. Give out.

Fragment slot area (FS1 to FS
m) 38a is composed of a 52 octet long fragment control area 460 transmitted by the base station and a 311 octet long fragment slot transmission area 470. The fragment slot transmission area 470 is set in the fragment control area 460. The transmission information is transmitted by the wireless terminal designated by the address. M fragment slot areas are formed in one communication frame, and the number m is the FS in the frame control area FC.
The N field 334 notifies each wireless terminal.

Each fragment control area 460 includes a preamble 41 having a length of 40 octets, a field flag 45 having a length of 4 octets, and other control information areas having a total length of 8 octets. The other control information area is a 6-octet-long assigned address (ASAD) field 48 in which a MAC address indicating the terminal device that has acquired the transmission right of the fragment slot is set, and the attribute of the fragment (“NFD” shown in FIG. ”,“ BRD ”, or“ SRD ”), and a 1-octet long CRC field 43d for checking a transmission error in the fragment control information area. , These pieces of information are set by the base station. The address (ASAD) field 48 also serves as an address display of the transmission source device of the fragment information to the destination device.

The fragment slot transmission area 470 is
The preamble 50 has a length of 40 octets, the field flag 51 has a length of 4 octets, and the other transmission information area has a length of 267 octets. The other transmission information area is a MAC indicating the destination device of the fragment information.
A 6-octet destination address (DADD) field 52 for setting an address and a 2-octet fragment information length (FILG) for indicating the effective length (8 bits) of the subsequent fragment information (FI) 54 in octet units. ) Field 472, fragment information (FI) 54, and 4-octet length CRC field 55 for checking a transmission error in fragment slot transmission information area 470. Set by the terminal. The above F
The ILG field 472 is the fragment information (FI).
The data block set in the field 54 includes 2-bit position information (for example, the first block, the intermediate block, and the last block) for indicating in the transmission message, and a 6-bit fragment (data block) sequence number.

Each fragment response area (AS1 to AS
m) is a 40-octet long preamble, a 4-octet long field flag, and "Reception success: AC" for each type ("individual communication" or "lawful communication") shown in FIG.
And an area for setting a response pattern of one octet length indicating "K" or "reception failure: NAK". This information is sent by the fragment destination device,
As a result, the base station is notified of the reception result of the corresponding fragment slot area.

As shown in FIG. 19, the base station controls the retransmission of a predetermined fragment corresponding to the response result from the destination device. Note that the details of the retransmission control performed here are shown in Table 4 and FIG. 12 in the above-mentioned material RCS 92-37 “Study of access control method suitable for wireless LAN” of the Institute of Electronics, Information and Communication Engineers wireless communication system research group. Therefore, detailed description is omitted here.

In the present embodiment, since transmissions from a plurality of wireless terminals may collide during broadcast communication in the above area, each terminal device only performs NAK response during broadcast.
The base station determines NAK recognition based on the presence / absence of carriers in the area.

A request display pattern having a length of 2 octets is set in the request display area (RI) located at the end of each frame. In this area (RI), a wireless terminal (hereinafter, referred to as an active terminal) that has data to be transmitted and whose reservation counter is within the reservation window value transmits the request display pattern. As the request display pattern, for example,
"00110011 00110011" is used.

In the request display area, transmission requests from a plurality of wireless terminals having transmission data collide with each other. Therefore, the base station determines whether or not there is a transmission in this area based on the presence / absence of a carrier. The base station, which recognizes from the carrier state in this area that there is a terminal device that has not reached the reservation window value and wishes to transmit, uses the RCI 332 of the next frame within a predetermined number of request cycle limits. , And notifies each wireless terminal device that the same request cycle continues.

FIG. 20 shows a processing procedure of a request cycle in each wireless terminal.

Upon receiving the frame flag (FF) 34 transmitted by the base station, each wireless terminal recognizes each area (field) in the frame on the basis of this and performs the processing operation as follows in correspondence with the area. To do.

The RCI area 332 receives the request cycle identifier (RCI) (step 332-1),
If RCI = "0", it is determined that a new request cycle has been entered (332-2), and the reservation counter (RCT) is reset.

In the request slot area (RS) R3, if there is a data transmission request to the wireless terminal (step 440-1), the value of the reservation counter RCT is compared with the reservation window value (RWD) (440). -2).
Here, when there is a relationship of RCT <RWD (active state), n request slots RS1 to RSn
Request is transmitted to one slot RSj arbitrarily selected from (440-3), and then the request is successful in the response slot AIj corresponding to the slot RSj in the request response area R2 (that is, transmission right). It is determined whether or not the reservation has been completed (440) (440
-4). If it is confirmed that the request is successful, the reservation counter RCT is incremented by 1 (440-5).

In the request display area (RI), the presence / absence of a transmission request is checked (442-1). If there is a transmission request and the own terminal is in an active state (442-2),
A request display pattern is transmitted (442-3).

FIG. 21 shows a request cycle management procedure 444 in the base station.

When the base station detects a transmission request from the wireless terminal in the request display area RI (step 444-2), it compares the value of the request cycle counter (RCC) with the request cycle window value (RCW) (444). −
3) If RCC <RCW, the new RCI value obtained by adding 1 to the value of the request cycle identifier (RCI) 332 of the frame is added to the RCI of the next frame.
The data is transmitted in the area 332 (444-4). by this,
Notify each wireless terminal that the same request cycle continues. On the other hand, when the transmission request (reservation) from the wireless terminal is not detected in the request display area RI (444-).
5) or when RCC = RCW (44
In 4-6), the value "0" is set in the RCI area 332 of the next frame, and the value of the request cycle counter RCC is reset (444-7).

The second embodiment has shown the method of controlling the number of reservations by the window in order to realize fair access in the divided channel reservation method. Next, a third embodiment of the present invention will be described in which the slotted aloha system is applied to the access multiplex system in which each wireless terminal directly transmits data without reserving the transmission right.

FIG. 22 shows the frame structure of the third embodiment. This frame is a frame control area (FC) 480.
And an uplink fragment slot area (UFS) 48 used for communication from the wireless terminal to the base station which serves as a relay station.
1, a request display area (RI) 482, and a downlink fragment slot area (DFS) 483 used for communication from the base station to the destination wireless terminal, and the base station stores the contents of the frame control area (FC) 480. To notify the wireless terminal of the timing of each frame. .

The frame control area (FC) 480 is
Basically, it has the same structure as the second embodiment shown in FIG. 15, and in this embodiment, the RSN region 333 shown in FIG.
The number j of fragment slots included in the UFS area 481 is set in the field, and the number k of fragment slots included in the DFS area 482 is set in the FSN area 334.

Similar to the second embodiment, the wireless terminal (active terminal) having the right to request data transmission in the UFS of the next frame operates in the request display area (RI) 482. The base station controls the request cycle depending on whether or not there is a transmission from the terminal device by RI.

On the other hand, the terminal devices in the active state whose reservation counter is within the window value are the first to the first in the uplink fragment slot area (UFS) 481.
An arbitrary slot is selected from the j-th fragment slot, and data is directly transmitted to the slot regardless of access permission from the base station. The theoretical maximum theoretical utilization rate of the UFS area 481 is about 38% on the basis of collision (competition) of data transmitted from a plurality of terminals, and therefore the downlink fragment slot area (DFS)
The number k of slots may be set to about 2.6 times the number j of slots in the uplink fragment slot area (UFS).

FIG. 23 is a block diagram showing an example of the detailed configuration of the base station. Compared with the second embodiment described above, the functions of the frame structure creation unit 484 and the protocol processing unit 485 are different.

Reference numeral 486 denotes a wireless module, which performs modulation / demodulation of a baseband signal and transmission / reception processing at high / intermediate frequencies, and supplies a carrier signal 487 detected from the received signal to a protocol processing unit (microprocessor). 488
Is a serial / parallel (S / P) conversion circuit that converts 1-bit received data into 8-bit parallel data based on a field flag (FIF) transmitted by the wireless terminal, and 489 is B
An error correction circuit that performs 1-bit error correction using a CH correction code is shown. The corrected data is input to the CRC processing circuit 490, and error detection is performed for each area.
The error detection result is sent to the protocol processing unit 485 together with the received data.

The protocol processing unit 485 decodes received data contents, request cycle control, transmission right reservation / allocation processing, transmission start, retransmission control, transmission data creation, relay data segmenting / reassembling control, and position registration database. A registration process to the (DB) 491 is executed.

Reference numeral 493 is a backbone network access processing circuit corresponding to the backbone interface 211 shown in FIG. 13, and performs interface processing with the backbone LAN 1 such as Ethernet or Token Ring. The transmission / reception data to / from the backbone network is transmitted in the transmission buffer 4
94 and the receive buffer 495. Location registration DB4
Reference numeral 91 stores management data such as a MAC address of a wireless terminal located in an area (cell) covered by this base station. The filtering circuit 496, based on the management data stored in the position registration DB 491,
It performs filtering processing of transmission / reception data on the backbone LAN side and the wireless side.

When data is transmitted from the base station to the wireless terminal, the protocol processing section gives a transmission instruction signal 497 to the frame structure creation control circuit 484, and the control circuit 48 is operated.
Under the control of No. 4, first, the preamble pattern information generated by the preamble addition circuit 498 is supplied to the wireless module. Meanwhile, with respect to the transmission data output by the protocol processing unit, the CRC generation circuit 499 generates an error correction code, the error correction circuit 500 inserts the CRC code into the transmission data, and these are transmitted to the transmission buffering circuit unit 501. Store. The data stored in the buffering circuit unit is converted by the parallel / serial (P / S) conversion circuit 502, and then, under the control of the frame structure generation control circuit 484, following the preamble, the wireless module 48.
6 and is transmitted to the air.

In the present embodiment, for example, the protocol processing unit 485 is composed of a 32-bit microprocessor, and the other parts are realized by a dedicated IC.

FIG. 24 is a block diagram showing the detailed structure of the communication processing unit of the wireless terminal device. The function of the communication processing unit is similar to that of the transmission processing unit of the base station shown in FIG. 23. Therefore, in order to simplify the explanation, the same elements as those of FIG. In particular, the block portion having a different function will be described in detail.

The S / P conversion circuit 488 converts the received signal in the following specific area into parallel data by detecting the field flag (FIF) and the frame flag (FF). The timing generation control circuit unit 504 recognizes the timing of each frame generated by the base station based on the frame flag (FF) detection signal 503 supplied from the S / P conversion circuit 488, and determines the transmission data transmission timing. Synchronize to the frame. When the protocol processing unit 505 decodes the content of the received data and receives the data addressed to the own terminal, the protocol processing unit 505 decodes the received data.
Transfer to 6. It also executes processing operations such as request issuance, request display, transmission activation, control for data retransmission in response to instructions from the base station, transmission data creation, base station recognition and location registration notification processing, etc. To do. In the wireless terminal, the error rate of the data transmitted by the base station is estimated from the number of times of CRC anomalies, and if the error rate exceeds a predetermined value, another cell is moved from one cell area in which it is located to another cell area. It is determined that the mobile station has moved to the area, and a location registration request is issued to the new base station.

FIG. 25 shows the overall structure of a communication system showing the fourth embodiment of the present invention. In FIG. 25, the base stations 3 a and 3 b are connected to each other via the backbone transmission line 1. The base stations 3a and 3b respectively include transmitting antennas 9-1 and 8-1 and receiving-only antennas 9-2 to 9-.
5, 8-2 to 8-5.

These reception-only antennas are connected to the base station by a cable (for example, a signal line 9-2-1) and cover an area having a radius of about 3 m (for example, 9-2-2). I am trying. Each coverage area has a shorter radius than the cell 4a of the second embodiment described above, and for example, the transmission of the wireless terminal 2b located immediately below the antenna and the transmission of the wireless terminal 2e located at the edge of the coverage area. In the case of collision, the size is set so that an error of 1 bit or more occurs in each transmission information on average. In the present embodiment, an area having a combined coverage area of a plurality of reception-only antennas connected to one base station corresponds to one cell, and this cell is covered by one transmission-only antenna.

Each reception-dedicated antenna is a reception unit (reception-dedicated antenna section) including the antenna 418 in the block diagram shown in FIG. 23, the reception section of the radio module 486, the error correction circuit 489, and the CRC processing circuit 490. ). In each reception-only antenna unit, for example,
When the frame structure shown in FIG. 15 is adopted, the data of the request area R3 is received, and when the frame structure shown in FIG. 22 is adopted, the data of the uplink fragment slot area (UFS) 481 is received. The protocol processing unit 485 provided in each base station processes received data from a plurality of reception-dedicated antenna units and transmits transmission data from one transmission-dedicated antenna. When the frame structure shown in FIG. 15 is adopted, the content of the request response area R2 is transmitted from the transmitting antenna 9-1, so that the request response area is secured for each receiving antenna.

FIG. 26 is a block diagram showing another embodiment of the wireless module transmitter of the wireless terminal according to the present invention.
This wireless module has the system configuration shown in FIG.
Alternatively, it is used when the frame structure shown in FIG. 22 is adopted.

The transmission data 412 is the information modulation circuit section 41.
Modulation using QPSK is performed in step 3, and the modulated output signal and the carrier wave output from the carrier wave generation circuit section 414 are multiplied by the multiplier 415, and then amplified to a predetermined level by the RF amplification circuit section 416. , And transmitted from the antenna 418.

Generally, the transmission power from the antenna is RF
It can be changed by controlling the gain of the amplifier placed in the final stage of the amplification circuit unit 416. In the present embodiment, assuming that there is a wireless terminal located directly below the base station and a wireless terminal located at the edge of the cell, when the transmission signals of the two collide, the terminal located at the cell edge is A first transmission power that can survive the competition with the terminal located directly below the base station, a second transmission power that loses the competition with the latter, and a third transmission power that is equal to or larger than the second transmission power. Is prepared and the protocol processing unit 506 shown in FIG.
However, one transmission power is selected from these three types of power according to the situation, and the gain of the final stage amplifier is set to the control signal 4
I am going to change it by 17.

In the case of the frame structure shown in FIG. 15, the protocol processing unit 506 randomly selects the first or second transmission power in the request area, and selects the third transmission power in the other wireless terminal transmission areas. Then, the transmission operation is performed. In the case of the frame structure shown in FIG. 22, UFS is used.
In the region, the transmission operation is performed by randomly selecting the first or second transmission power. According to the present embodiment, the unfairness does not occur except when the transmission signals transmitted with the same transmission power collide with each other, so that the request cycle control of the base station is unnecessary. Therefore, RCI3 in the FC area of each frame
32 may be fixed to “0” or deleted.

As a modification of the above-described method for controlling the transmission power, the transmission power randomly selected in the above-mentioned embodiment may be selected according to the priority given in advance to each wireless device, for example. . In this case, by preparing n types of transmission power that can be selected by the control signal, transmission control can be performed with n levels of priority.
As another modification, for example, the antenna structures or positions of the wireless terminals and the base stations may be installed such that the distance between the wireless device and the base station is substantially shortened according to the priority order of the wireless terminals. Good.

[0169]

As is apparent from the above embodiments, according to the present invention, a plurality of slave devices (wireless terminals) transfer information using fragments under access control by the main device (base station). In the communication system for performing multiple access, multiple access with good communication efficiency can be realized.

According to the present invention, the dynamic transmission power control depending on the distance between the slave device and the master device is not performed,
It is possible to realize fair and efficient access control, and to provide a simple priority control method that does not depend on processing at the MAC layer level in the access control method on the premise that transmission requests from a plurality of slave devices collide.

[Brief description of drawings]

FIG. 1 is a network configuration diagram showing an embodiment of a communication system according to the present invention.

FIG. 2 is a diagram showing a first embodiment of the structure of frames and fragments used in a wireless communication section in the present invention.

FIG. 3 is a diagram showing a communication procedure in intra-cell communication performed between a wireless terminal (slave device) and a base station (main device).

FIG. 4 is a diagram showing a list of reception response operations in the communication procedure.

FIG. 5 is a diagram showing the relationship between upper frames and fragments transmitted by each wireless terminal.

FIG. 6 is a diagram showing the relationship between fragments and correction blocks.

FIG. 7 is a state transition diagram for explaining frame timing control in the base station.

FIG. 8 is a state transition diagram regarding a request operation in a wireless terminal.

FIG. 9 is a state transition diagram regarding a transmission operation in a wireless terminal.

FIG. 10 is a diagram showing a processing procedure for request acceptance determination in the base station.

FIG. 11 is a diagram showing a processing procedure for access control in a base station.

FIG. 12 is a diagram showing a procedure of a reception process in a wireless terminal.

FIG. 13 is a block diagram showing the basic configuration of a base station.

FIG. 14 is a block diagram showing a basic configuration of a wireless communication unit of a terminal device.

FIG. 15 is a diagram showing a second embodiment of the communication frame structure used in the wireless communication section in the present invention.

FIG. 16 is a diagram showing a relationship between acceptance status types and transmission contents.

FIG. 17 is a diagram showing the relationship between fragment attribute types and transmission contents.

FIG. 18 is a diagram showing a relationship between response types and transmission patterns.

FIG. 19 is a diagram showing a correspondence relationship between a response result and retransmission control.

FIG. 20 is a diagram showing a processing procedure of a request cycle in a wireless terminal.

FIG. 21 is a diagram showing a request cycle management procedure in the base station.

FIG. 22 is a diagram showing a third embodiment of the frame structure used in the wireless communication section in the present invention.

FIG. 23 is a block diagram showing a configuration of a base station according to a third embodiment.

FIG. 24 is a block diagram showing details of a communication processing unit on the wireless terminal side in the third embodiment.

FIG. 25 is an overall system configuration diagram showing another embodiment of the wireless communication system according to the present invention.

FIG. 26 is a block diagram showing another embodiment of the transmitter of the wireless module.

[Explanation of symbols]

2 ... Wireless terminal, 3 ... Base station, 10 ... Access right grant request, 11 ... Communication slot allocation, 12 ... New data transfer, 13 ... Response, 14 ... Base station resend, 15 ... Resend request slot, 16 ... Source resend , 30 ... Communication frame, R1
... synchronization area, R2 ... request response information area, R3 ... request area, R4 ... information transfer area, 32 ... protection time,
33 ... Preamble, 34 ... Unique word, 35 ... Request response slot, 37 ... Request slot, 3
8 ... Fragment slot, 39 ... Response slot, 43
... request information, 43a ... request number, 43b ... request source address (request address area), 43c ... request fragment number, 43d ... request information error detection code, 46 ... new information display, 47 ... fragment number, 4
8 ... Source address (assigned address), 52 ... Destination (destination) address, 53 ... Data length, 54 ... (Fragment) information area, 55 ... Fragment error detection code, 5
9 ... Response information, 211 ... Backbone interface,
212 ... Radio section reception control circuit, 213 ... Radio section transmission control circuit, 214 ... Frame processing section, 215 ... Request control section, 216 ... Relay determination, 217 ... Fragment buffer / control section, 219 ... State control section, 311 ... Terminal Interface 314 ... Frame processing unit, 315 ... Reception determination / reassembly processing unit, 316 ... Frame buffer / control unit, 317 ... Fragment processing unit, 319 ... Status control unit, 331 ... Base station identifier, 34 ... Frame flag, 3
32 ... Request cycle identifier, 42 ... Field flag, 43e ... Request attribute, 451 ... Reception request address, 452 ... Reception state, 462 ... Fragment attribute, 472 ... Fragment information length, 480 ... Frame control, 481 ... Uplink fragment slot, Four
82 ... Request display area, 483 ... Downlink fragment slot, 484 ... Frame structure creating section, 485 ... Protocol processing section, 486 ... Wireless module, 487 ... Carrier detection, 488 ... S / P conversion, 489 ... Error correction section, 490 ... CRC processing unit, 491 ... Location registration database, 493 ... Backbone network access processing unit, 494 ... Transmission buffer, 495 ... Reception buffer, 496 ... Filtering, 497 ... Transmission instruction signal, 398 ... Preamble addition unit, 499 ... CRC generation unit , 500 ... Error correction code addition unit, 501 ... Transmission buffering unit, 502, ... P / S
Conversion unit, 503 ... FF detection signal, 504 ... Timing generation unit, 506 ... Upper interface, 9-2 ... Reception dedicated antenna, 413 ... Information modulation unit, 414 ... Carrier generation unit, 415 ... Multiplication unit, 416 ... RF amplification unit 417 ... Gain control signal.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number in the agency FI Technical indication location H04Q 3/58 104 9076-5K (72) Inventor Genichi Ishii 1-280 Higashi Koikeku, Kokubunji, Tokyo Central Research Laboratory, Hitachi, Ltd. (72) Hidehiko Shigezai, 1-280, Higashi Koikekubo, Kokubunji, Tokyo (72) Central Laboratory, Hitachi, Ltd. (72) Shuichi Adachi, 1 Horiyamashita, Hadano, Kanagawa Prefecture Factory Kanagawa factory

Claims (26)

[Claims] 1. A main device for controlling a transmission right and a plurality of slave devices, wherein at least a synchronization signal area, a request area, and an information transfer area are used for communication between the main apparatus and each slave device. In the communication system using the communication frame, a slave device in which the master device sends information in the sync signal area at the beginning of each communication frame and tries to perform data transmission is defined after the sync signal area. Output the information showing the access request in the request area,
The master device sends the permission information for the access request to the information transfer area following the request area, and the slave device receiving the permission information causes the slave device to perform a predetermined operation within the information transfer area defined after the permission information. A communication method characterized in that the transmission data is sent to the field. 2. The request area comprises a plurality of request slots, and a slave device which is going to perform data transmission outputs information indicating the access request to any of the request slots. The communication method according to claim 1. 3. The information transfer area comprises a plurality of slots, and a slave device which is going to perform data transmission specifies the number of slots required for data transmission and outputs information indicating the access request. The device performs the permission information for the access request in each slot in the information transfer area, and the slave device receiving the permission information sends the transmission data to a predetermined field in the slot in which the permission information is located. The communication system according to claim 1 or 2, characterized in that. 4. The information indicating the access request includes an address of a slave device, and the permission information transmitted by the master device includes an address of the slave device obtained from the access request information. Alternatively, the communication method described in 3. 5. A master device for controlling a transmission right and a plurality of slave devices, wherein at least a synchronization signal area, a request area and an information transfer area are used for communication between the master apparatus and each slave device. In a communication system using a communication frame, the information transfer area is composed of a plurality of pairs of information transfer slots and response slots following the request area,
The slave device that is going to perform data transmission sends an access request in the request area defined after the synchronization signal area, and the main device sends permission information for the access request for each of the information transfer slots. The slave device receiving the permission information sends the destination address and the transmission data in the information transfer slot containing the permission information, and the destination device sends the response information to the response slot paired with the information transfer slot. A communication method characterized by that. 6. The request area comprises a plurality of request slots, and a slave device which is going to transmit data outputs information indicating the access request to any one of the request slots. The communication method according to claim 5. 7. The information indicating the access request includes the address of the slave device, and the permission information transmitted by the master device includes the address of the slave device obtained from the access request information. Communication method described in. 8. The main device retransmits information including a destination address and transmission data which have already been received, to a next information transfer slot, according to response information included in the response slot. The communication method according to 5, 6, or 7. 9. A main device for controlling transmission right,
In a terminal device that communicates via a wireless channel with a communication frame that has at least a synchronization signal area, a request area, and an information transfer area, and that includes a plurality of information transfer slots in the information transfer area, Means for transmitting an access request to the request area identified by receiving the signal in the synchronization signal area of the communication frame, and permission information sent by the main device in any information transfer slot of each communication frame, A terminal device for transmitting transmission data including a destination device address at a predetermined field position in the information transfer slot when the terminal device receives the data. 10. The access request transmission means outputs the information indicating the access request to any one of a plurality of request slots defined in advance in the request area. The terminal device according to claim 9. 11. The access request transmitting means transmits, as the access request information, information including an address unique to the device itself and the number of information transfer slots required for data transmission. Item 11. The terminal device according to item 9 or 10. 12. When a destination device address field included in the information transfer slot of each communication frame detects an address unique to the device itself, the device further comprises means for receiving the transmission data of the information transfer slot. The terminal device according to claim 9, 10 or 11. 13. When the transmission data to be received and processed cannot be normally received, the data is normally transmitted to a response slot defined in advance at a predetermined position subsequent to the information transfer slot in which the transmission data is located. 13. The terminal device according to claim 12, further comprising means for transmitting response information indicating that it was not received. 14. A multiple access system of a sub-network comprising a plurality of slave devices that communicate with each other using a common communication frame as a medium, and a master device for controlling the access right of each slave device to the communication frame. Then, each slave device having a transmission request sends a transmission request to the request area in the communication frame identified based on the synchronization signal of each communication frame sent by the master device, and the master device is In the information transfer area defined after the request area in the communication frame, a device identifier for designating the slave device that has obtained the access right determined according to the transmission request is transmitted, and one slave device corresponding to the device identifier is transmitted. A multiple access method, wherein the device sends data to a predetermined area following the device identifier. 15. A main device which performs access control and a plurality of terminal devices, and communication between the terminal devices or between each terminal device and the main device is performed by at least a synchronization signal area, a request area and an information transfer area. In a communication method performed via a communication frame having the following, the information transfer area of each communication frame includes a plurality of information transfer slots and a response slot provided immediately after each information transfer slot, and the main device is The slave device that sends the information of the synchronization signal area at the beginning of each communication frame and tries to perform data transmission outputs access request information to the request area identified by the reception of the synchronization signal area. , The master device provides permission information for designating the slave device to which access is permitted, to each information transfer slot in the information transfer area following the request area. The slave device that was given at the beginning of the
The destination address and the transmission data are transmitted in a predetermined area within the information transfer slot including the permission information, and the slave device which is the destination transmits the response information in the response slot paired with the information transfer slot. Characteristic communication method. 16. The access request information output to the request area includes address information of a slave device as a request source,
The permission information provided by the master device includes address information for specifying a slave device as a request source, and the address information is transmitted in a field indicating a sender device which is defined in advance in the information transfer slot. 16. The communication method according to claim 15, wherein. 17. The request area comprises a plurality of request slots, each slave device that is going to transmit data sends the access request information to any one of the request slots, and the master device is the same. When it is detected that the access request information from a plurality of slave devices collides in the request slot, the communication frame is defined in a predetermined control field located before the request area in the next generated communication frame. The communication method according to claim 15 or 16, wherein control information for limiting slave devices that can be requested by is output. 18. Each slave device sends the access request information to a specific request slot corresponding to each slave device in each communication frame, and an access request from another slave device is sent in the request slot. 18. The communication system according to claim 17, wherein when there is a conflict with information, a re-access request to be made in a subsequent communication frame is made to another request slot selected by a predetermined algorithm. 19. A communication system comprising a plurality of slave devices and a master device for controlling the access right of each slave device to a communication channel, wherein each communication frame communicated on said communication channel is transmitted from said master device. A sync signal area for sending a sync signal,
A request area consisting of a plurality of request sections for transmitting an access request from each slave device located after the synchronization signal area, and a slave device, which is located after the request area and is permitted to access, for transmitting transmission information. An information transfer area including a plurality of information transfer sections, and the information transfer area has a plurality of response sections for transmitting response information indicating success or failure of transmission information reception corresponding to each of the information transfer sections. However, when each slave device fails to receive the transmission information addressed to itself transmitted in any of the information transfer intervals, a predetermined reception interval indicating a reception failure corresponding to the information transfer interval is given. When the transmission source device or the main device detects a reception failure in the response section, it retransmits the transmission information in another information transfer section located after the response section. A communication method characterized in that 20. In a communication network in which communication between a master device and a plurality of slave devices in a wireless section is performed through a communication frame of a predetermined form, a slave device having data to be transmitted is included in each communication frame. Request the transmission right in the defined request area, and reserve the transmission right in the next communication frame in the predetermined area defined in the above communication frame as long as the accumulated number of transmission right requests does not exceed the limit number. In response to the transmission request received in the request area, the main device permits the requesting slave device to transmit data in the specified information area in the communication frame, and the permitted slave device is Data is transmitted in the specified information area, and the master device resets the accumulated number of transmission right requests according to a predetermined reset cycle and the reservation status of the transmission right from the slave device. Of the transmission right request is sent to the next communication frame, and when the received control information indicates reset permission, the slave device accumulates the number of transmission right requests. Is reset, and the slave device, which has been in the waiting state until the cumulative number of times exceeds the limit number, restarts the request for the transmission right. 21. A communication system comprising a master device and a plurality of slave devices that wirelessly communicate with each other, wherein each slave device transmits data according to a communication frame structure generated by the master device, wherein each communication frame comprises: An identification area for transmitting information indicating a frame delimiter from the main device, a request area for transmitting a transmission request from a slave device having transmission data, and a right or right of transmission of the transmission request from the main device The request response area for sending information indicating allocation of data, the data transfer area for sending data from the slave device to which the transmission right is allocated, and the request area of the next frame for the slave request A request reservation area for transmitting request reservation information from the device, and a constraint condition for the request area or the request reservation area from the main device A communication method comprising a request control area for transmitting control information. 22. A channel (uplink) for transmitting information from a slave device to a master device in a communication frame communicated in a wireless section between the master device and a plurality of slave devices, and the slave device from the master device. And a channel for transmitting information to the slave (downlink), and each slave device sends information to a part of the uplink on the premise that competition with other slave devices occurs, The maximum number of data transmission requests that can be made within a predetermined cycle period is set for each slave device, and the number of data transmissions performed by the slave device with a transmission request using the uplink is the above-mentioned limit number. Only if
In the case where the main device is notified of the information requesting the transmission request in the communication frame in the predetermined area of the uplink, and the main device detects that the transmission request notification information is not in the predetermined area of the communication frame. , Before the expiration of the predetermined cycle period, notifies the slave device of the update of the cycle period in a predetermined area of the downlink, each slave device is subject to the restriction every time the cycle period update notification is given. Communication method characterized by resetting the number of data transmission requests. 23. A channel (uplink) for transmitting information from a slave device to a master device in a communication frame communicated in a wireless section between the master device and a plurality of slave devices, and the master device to the slave device. And a channel for transmitting information to the slave (downlink), and each slave device sends information to a part of the uplink on the premise that competition with other slave devices occurs, The communication frame has an identification area for giving information indicating at least a delimiter of the frame from the main device to the slave device, an uplink data area for transmitting data from the slave device, and data from the main device to the destination slave device. A downlink data area for relaying, a request display area for notifying the master device of the transmission of the next frame data transfer area to the master device, and a slave device A communication system characterized by having a request control area for notifying transmission conditions in the uplink data area or the request display area. 24. A master unit and a plurality of slave units wirelessly communicate with each other, and each slave unit having data to be transmitted requests a transmission right to the master unit, and an information transmission area from the master unit is transmitted. In a communication system in which data transmission is performed after allocation, the main device is distributed and arranged in the cell area around the transmission / reception processing section, the transmission antenna section that covers the cell area, and the transmission antenna. It is composed of a plurality of receiving antenna units, and assigns a transmission right to each slave device via the transmitting antenna unit in response to a transmission right reservation request from the slave device received by the plurality of receiving antennas. Communication method. 25. A master device and a plurality of slave devices wirelessly communicate with each other, and a slave device having data to be transmitted requests a transmission right to the master device, and an information transmission area is allocated from the master device. In the communication system in which the data transmission operation is performed after waiting, each slave device has a transmission unit that can switch the transmission power level in multiple steps, and determines the transmission power each time a transmission right is requested. A communication method characterized in that a transmission request is made by the transmission power. 26. A channel (uplink) for transmitting information from a slave device to a master device in a communication frame communicated in a wireless section between the master device and a plurality of slave devices, and from the master device to the slave device. And a channel for transmitting information to the slave (downlink), and each slave device sends information to a part of the uplink on the premise that competition with other slave devices occurs, Each of the slave devices includes a transmission unit capable of switching the transmission power level in a plurality of steps, and at the time of the transmission operation performed in the uplink, the transmission power is selected and transmitted according to a priority determined in advance for each slave device. A communication method that operates.